Study on stability of poly(3-hexylthiophene)/titanium dioxide composites as a visible light photocatalyst

Highlights: • P3HT/TiO₂ composites can degrade MO effectively under visible light irradiation. • The stability of P3HT/TiO₂ composites was studied systematically. • The composites were stable to 10 h of photodegradation of MO under visible light. - Abstract: Conjugated polymer/TiO₂ composites are promising visible light photocatalysts for solar chemical conversion processes in the field of environmental chemistry for decomposition of organic compounds in water and air. In consideration of the fact that conjugated polymers are also organic substances, particular attention must be focused on the stability of conjugated polymer/TiO₂ composites, which has not been laid enough emphasis upon so far. Poly(3-hexylthiophene)/titanium dioxide (P3HT/TiO₂) composites, as a representative of conjugated polymer/TiO₂ photocatalysts, were prepared by combining chemical oxidative polymerization method and physical blending technique. The stability of the composites was systematically studied by comparative analysis of the physical and chemical structure of P3HT/TiO₂ composites before and after the photocatalytic reaction. As confirmed by the results of high-resolution transmission electron microscopy (HRTEM), scanning electron microscope (SEM), ultraviolet-visible diffuse reflectance spectroscopy (UV–vis DRS), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), the P3HT/TiO₂ composites were quite stable to 10 h of photodegradation of methyl orange (MO) under visible light, maintaining both their physical and chemical structure